This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Prohead RNA (pRNA) of the Bacillus subtilis bacteriophage [unreadable]29, a 174-base transcript of the far left end of the genome, is an essential component of the [unreadable]29 DNA packaging motor. A novel pRNA multimer binds to the head-tail connector of the precursor protein shell (prohead), and subsequent binding of the ATPase gp16 to pRNA constitutes the motor that translocates the 19 kilobase pair DNA-gene product 3 complex (DNA-gp3). ATP hydrolysis drives DNA-gp3 packaging, and one ATP is used to package two base pairs of DNA. The discovery of pRNA in [unreadable]29, the leading system for mechanistic studies of viral DNA packaging, has general significance in that common mechanisms may be used in packaging double-stranded DNAs of the tailed bacteriophages and certain animal viruses. The role for pRNA as a transient structural component and catalyst in DNA packaging extends the evolvement of novel structural and biochemical functions for RNA.